(1) Field of the Invention
The present invention relates generally to papermaking and, more particularly, to an additive and a method for determining the effective amount of the additive needed to control the detrimental effects of secondary recycled contaminates which occur frequently during reprocessing recycled paper.
(2) Description of the Prior Art
Much of the materials that go into waste landfills are paper and paper based products, such as packaging. As landfill space becomes harder to find, recycling of paper products has been encouraged or dictated by federal, state and local governments. However, many problems arise in recycling paper fibers that would not have existed in making paper using virgin fibers. For example, a major problem is xe2x80x9cstickiesxe2x80x9d which is the nickname for secondary fiber contamination.
Stickies are sticky spots, which show up on the paper and on the papermaking machine. Stickies are very detrimental to the paper making process. They interfere with drainage on the forming table and plug up the press felts and the dryer felts, which knocks the efficiency of the pressing and drying down substantially, thereby driving energy costs up. Stickies can also cause actual fiber breaks and sheet breaks on the paper machine and can actually bring a whole machine down.
A sheet break is the breaking of the continuous paper making process. When there is a sheet break on the machine, the fiber must be sent back to the refiners chest until the break can be rethreaded and the machine restarted. Because of the tremendous capital investment necessary for a papermaking machine, when the machine is not making any paper, the Company is not making any money.
Various additives have been tried to reduce the stickies but have met with limited success since the variability in the input for a recycled papermaking process makes choosing the right amount of additive for ever changing conditions extremely hard. Most of these attempts appear to be using strictly at homo-polymers and have met with limited success.
Thus, there remains a need for a new and improved additive to control the detrimental effects of secondary recycled contaminates which occur frequently during reprocessing recycled paper while, at the same time, providing a method for determining the effective amount of the additive.
The present invention is directed to an additive for controlling the detrimental effects of secondary recycled contaminants in the papermaking process. In the preferred embodiment, the additive includes a first low molecular weight, cationic water-soluble polymer and a second low molecular weight, cationic, water-soluble polymer, wherein the first low molecular weight, cationic, water-soluble polymer and the second low molecular weight, cationic, water-soluble polymer are co-reacted.
In the preferred embodiment, the effective amount of the additive is determined by measuring about a 50 PPM reduction in soluble charge of the liquid base after adding the additive to the liquid base. In the most preferred embodiment, the reduction in soluble charge is between about 50 and 150 PPM as measured by determining the electrophoretic mobility of the liquid base with and without the additive.
Also, in the preferred embodiment, the first low molecular weight, cationic, water-soluble polymer and the second low molecular weight, cationic, water-soluble polymer are cross-linking and form a co-polymer structure.
The first low molecular weight, cationic, water-soluble polymer is a di-ammonium chloride polymer, such as DAD MAC, and the second low molecular weight, cationic, water-soluble polymer is a polyacrylamide. The molecular weight of the additive is controlled to be less than about 25,000 cps but greater than about 18,000 cps.
Accordingly, one aspect of the present invention is to provide an additive for controlling the detrimental effects of secondary recycled contaminants in the papermaking process, the additive containing an effective amount of a low molecular weight, cationic water-soluble polymer.
Another aspect of the present invention is to provide an additive for controlling the detrimental effects of secondary recycled contaminants in the papermaking process, the additive including: a first low molecular weight, cationic, water-soluble polymer; and a second low molecular weight, cationic, water-soluble polymer, wherein the first low molecular weight, cationic, water-soluble polymer and the second low molecular weight, cationic, water-soluble polymer are co-reacted.
Still another aspect of the present invention is to provide an additive for controlling the detrimental effects of secondary recycled contaminants in the papermaking process, the additive including: a first low molecular weight, cationic, water-soluble polymer; a second low molecular weight, cationic, water-soluble polymer, wherein the first low molecular weight, cationic, water-soluble polymer and the second low molecular weight, cationic, water-soluble polymer are co-reacted; and wherein the effective amount of the additive is determined by measuring about a 50 PPM reduction in soluble charge of the liquid base after adding the additive to the liquid base.
These and other aspects of the present invention will become apparent to those skilled in the art after a reading of the following description of the preferred embodiment when considered with the drawings.